{
  "abstract": "Introduction and Objectives PE is the third most common cardiovascular disease worldwide and is potentially life-threatening if not identified and treated early. Incidental PE (iPE) identified on non-dedicated thoracic imaging is increasing in incidence and clinical practice in verifying iPE is heterogeneous.Objectives Assess the prevalence of iPE and frequency of CT pulmonary angiography (CTPA) validation.Identify the diagnostic accuracy of iPE without CTPA validation and factors predicting false-positive diagnosis.Hypothesis Expert review could reduce the requirement for CTPA in confirming iPE.Methods We conducted single-centre retrospective analysis of 25,214 consecutive non-CTPA contrast-enhanced CT chest studies from over an 18-month period (01/12/2022–31/05/2024). Text string search of the initial radiology reports was used to identify iPE. Reports were classified by diagnostic certainty (levels 1 to 5) for iPE according to reported radiologist opinion and pertinent clinical data collected.An expert review of non-dedicated scans was performed by fellowship-trained thoracic subspecialists (HS, JCLR) blinded to confirmatory imaging. Subgroup analysis was performed for those receiving layered CTPA testing to validate iPE diagnosis.Results iPE was reported in 1%(n=260/25,214) of non-dedicated studies (51% female, 73±12 years). 25%(n=65/260) received confirmatory CTPA. 54%(n=35/65) of iPE were confirmed on CTPA. This indicates that 12%(n=30/259) were treated for false-positive iPE. Review reclassified 8%(n=22/259) of studies as indeterminate and requiring CTPA. Agreement between the expert review of the iPE scan and the ground-truth confirmatory CTPA diagnosis had a κ statistic of 0.78.False-positive studies reported lower diagnostic certainty than true-positives (p<0.001). Expert review of the subgroup receiving CTPA reclassified 37%, predicted CTPA ground-truth in 72% and confirmed artefact for 32%. Where the reporter was confident of iPE diagnosis, 93%(n=194/209) were true-positives according to expert review, where unconfident this was 26%(n=13/50).Mortality was high in this iPE group, primarily reflecting the underlying indication (predominantly metastatic malignancy) for the non-CTPA CT chest.Abstract P280 Figure 1(A) Sankey diagram showing original diagnostic certainty of non-dedicated CT identifying iPE not receiving CTPA follow-up and the subsequent expert of diagnoses. (B) Sankey diagram showing original diagnostic certainty of non-dedicated CT identifying iPE receiving CTPA follow-up and subsequent expert and CTPA classification of these diagnoses. Initial radiology reports identifying iPE were classified into 5 certainty levels on the basis of report language compared with published literature on reporting diagnostic certaintyConclusions iPE was reported in 1% of scans, with expert review confirming this for 80%. Diagnostic certainty in initial reports can stratify the likelihood of true-positive iPE, guiding targeted expert review to minimise unnecessary CTPA and treatment of false-positive iPE.",
  "authors": [
    {
      "affiliations": [
        "University of Bristol Medical School, Bristol, UK"
      ],
      "name": "CRT Kidson"
    },
    {
      "affiliations": [
        "Royal United Hospitals, Bath, UK"
      ],
      "name": "H Sohn"
    },
    {
      "affiliations": [
        "Royal United Hospitals, Bath, UK"
      ],
      "name": "J Page"
    },
    {
      "affiliations": [
        "Royal United Hospitals, Bath, UK",
        "Department of Health, University of Bath, Bath, UK"
      ],
      "name": "JCL Rodrigues"
    }
  ],
  "title": "P280 Incidental pulmonary embolism (iPE) and the value of CT pulmonary angiography follow-up versus expert review",
  "uid": "19fefa76-64b3-5d48-adc5-789144c8d680"
}